1. Field of the Invention
The present invention relates to a process cartridge for image forming apparatus and, more specifically, to a foolproof device used in an image forming apparatus, which prevents an installation error of the toner container in the developing device.
2. Description of the Related Art
A regular process cartridge for a laser printer is generally comprised of an electrophotographic photosensitive member, developing means, charging means, cleaning means, and a toner container. When the toner of the toner container used up, the whole assembly of the process cartridge becomes useless and must be thrown away. It is not economic to throw the whole assembly of the process cartridge away after empty of the process cartridge. Further, the waste process cartridge may cause pollution to the environment if it is not well disposed of.
The present invention has been accomplished to eliminate the aforesaid drawbacks. In one aspect, the present invention relates to a process cartridge, which enables the user to replace the toner container without throwing the other parts of the process cartridge away when the toner is used up. In another aspect, the present invention relates to a foolproof device that can be used in a process cartridge having a developing device and a toner container, which prevents leakage of toner due to an installation error of the toner container in the developing device. In one embodiment of the present invention, the foolproof device comprises a plurality of male engagement portions formed on the developing device of the process cartridge, a plurality of female engagement portions formed on the toner container, and a plurality of projections also formed on the toner container of the process cartridge. The male engagement portions are different in size. The female engagement portions are also different in size and fit the male engagement portions respectively. The foolproof device guides correct installation of the toner container in the developing device, preventing leakage of toner due to a wrong installation of the toner container in the developing device.